Insulating-coil and method of making same



J. E. MATEER.

INSULATING COIL AND METHOD OF MAKING SAME.

APPLICATION FILED SEPT- I, 1917- Pateflted Aug. 30, 1921.

lNVENTOR Jesse 5 Ma fear ATTORNEY WITNESSES UNITED STATES PATENT OFFICE.

JESSE E. MATEER, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

INSULATING-COIL AND METHOD OF MAKING SAME.

Application filed September .1, 1917. Serial no. 189,398.

To all whom it may concern:

Be it known thatv I, Jiassn E. MATEER, a citizen of the United States, and a resident of Wilkinsburg, in the county of Allegheny tor coverings, or, in other words, the coil insulation, with bakelite'and -to subject the coil, in this state, to heat whileunder pressure. 'Tape treated with varnish was thenwound upon the coil and, when the insulated coil was oversize, it was compressed until it was of the desired dimensions. While the aforementioned construction sometimes gave good service, the insulation frequently sepa rated from the coils on account of belng subjected to very high temperatures which sof ened thevarnish or impregnating compound,

thereby allowing the insulation to be separated from the coil. When this occurred, which happened frequently in-broad coils, it formed spaces between the coil and the separated insulating material, the dead air in which, being a very oor heat conductor, frequently permitted t e temperature of the coil to reach a dangerous value.

Another fault of the coil, as formerly insulated, was that the external surface of the coil was rough, which permitted particles of dust to'accumulate in the depressions there of. It is Well-known that accumulations of dust interfere with the proper cooling of coils and if, by chance, these accumulations are in the nature of metallic powders or other electrical conducting material, short circuits are. liable to develo in the coils. The object of my invention is to provide be economicall produced and the insulatlon of which wil firmly adhere under all conditions of commerclal service. At the same time, I produce coils which possess smooth external surfaces, thus precluding particles of dust from accumulating thereupon. Also, the external surface of each coil is so treated that it will not tend to adhere to surfaces with which it comes into Contact.

Figure l of the accompanying drawing is a plan view of a-coil constructed in accordance with my invention. Fig. 2 is a sectional perspective view of the coil shown in Fig. 1.

According to my invention, the coil is constructed by winding a plurality of conductors 1, into coilform. The individual conductors are separated from each other by strips 2 of absorptive insulating material, and, in addition, each conductor has an absorptive insulating coating 3, usually the cot- -ton cover customarily applied to conductors.

The superposed rows of conductors are insulated from one another by means of an insulating member 4:, which extends across substantially the entire width of the coil. When the coil has reached this stage of construc- Specification of Letters Patent. Patented Aug, 30, 1921,

tion, it is impregnated with a phenolic condensation product,'usually bakelite, and is subjected to heat while under mechanical pressure, thereby forming the conductors and the insulating material into a solid mass.

The coil is then wrapped with tape, or

some other suitable pervious insulating material 5 and is again impregnated with an insulating compound similar to that alread used to impregnate the coil and is covere on each face, with a layer of paper 6, which has been impregnated with a similar com-' pound. The coil is then heated, while under mechanical pressure exerted by shaping plates, and the result is a coil in which the insulating material around and between the individual conductors is integral with the exterior covering of tape and. paper and in which the conductors and the insulating ma terial form a solid 'mass.

On account of the insulatlng material,

which serves as a binder, being thesame.

throughout the coil, it will blend and become an integral mass on being heated under mechanical pressure and, being integral, the

exterior covering of tape and paper does not leave the conductors. The external layer of paper causes the coil to present a smooth external surface, thus precluding the accumulation of dust thereupon "and causing the coil to present a surface that does not tend to adhere to any surface with which it comes in contact.

Another advantage gained by using a phenolic condensation product in place of varnish is that, when drying, the phenolic condensation product tends to shrink the tape which it impregnates, thereby causing the tape to adhere more closely to the coil, while, on the other hand, varnish allows the tape to stretch, causing it to wrinkle and to sep-- arate from the coils at some points.

Another advantage of subjecting the coil to the step of heating under mechanical pressure that is exerted by the means of plates, is that the exterior surface of the coil is smoothed by the application of this mechani cal pressure which results in imparting a polished surface to the finished product, thereby insuring that particles of dust will not lodge in the interior irregularities of the coil. This feature has been found to be of great importance for formerly much of the overheating of such coils has resulted from the collection of particles of dust in the many slight irregularities formed on the surfaces of the coils.

While I have shown one form of my invention and described, in detail, one application of the same, it will be obvious to those skilled in the art that it is not so limited but is susceptible of various minor changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or are specifically set forth in the appended claims."

I claim as my invention:

1. An insulated coil comprising conductors, strips of pervious insulating material separating the conductors from one another, and layers of pervious insulating material surrounding the entire group of conductors, said layers of insulating material being impregnated with a hardened and a mechanically pressed and smoothed phenolic condensation product to form a permanently smooth exterior surface for said coil.

2. ,An insulated coil comprising a plural ity of conductors each separately wrapped n pervious insulating material and arranged in superimposed rows, insulated spacer strips of pervious material disposed between the rows and the several conductors of the rows, a wrapping of pervious insulating material inclosing the assembled conductors, and a wrapping of paper about the last mentioned wrapping of pervious material, all of the wrappings and spacer strips being impregnated with a hardened and mechanically smoothed phenolic condensation product.

3. The process of insulating coils which consists in separately wrapping conductors with pervious material, interposing strips of pervious material between the several conductors, wrapping the assembled conductors as a unit with pervious material, impregnating the material with a phenolic condensation product and subjecting the coil thus assembled to the simultaneous action of heat and pressure, wrapping the coil thus treated with additional pervious material and with an outer layer of paper all impregnated with a phenolic condensation product and subjecting the thus completely assembled coil to further heat and mechanical pressure to further unite all of its component parts.

a. The process of insulating coils which consists in providing an independent insulation for each conductor, interposing insulation between the several conductors, winding insulation about the entire body of conductors, winding paper about the last mentioned insulation, all of the insulation and windings being impregnated with a common binder, and compacting the thus assembled coil and hardening the binder of the insulation and wrapping by the simultaneous application of heat and mechanical pressure.

5. The process of insulating coils which consists in independently wrapping the several conductors constituting the coil, arranging the conductors in superimposed rows, positioning strips of insulating'material between the several conductors of each row, positioning aqcontinuous strip of insulating material between the conductors of one row and those of an adjacent row, impregnating the wrapping of the several conductors and the insulating strips with a phenolic condensation product, subjecting the body thus formed to the simultaneous action of heat and pressure, wrapping the body thus treated with further insulating material, including an outer layer of paper, impregnating this material with a phenolic condensation product and subjecting the body thus formed to the simultaneous action of heat and mechanical pressure to intimately unite all of its component parts.

6. The process of insulating coils which consists in separately wrapping conductors with pervious material, inter osing strips of pervious materal between t e several conductors, wrapping the assembled conductors, as a unit, withpervious material, impregnating the material with a phenolic condensation product and subjecting the coil thus assembled to the simultaneous action of heat and pressure, wrapping the coil thus treated with additonal pervious material and with an outer layer of paper, all impregnated with a phenolic condensation product and subjecting the thus completely assembled -coil to further heat and pressure to further meme-e ing the conductors in superimposed rows positioning strips of insulating material between the several conductors of each row, positioning a continuous strip of insulating material between the conductors of one row and those of an adjacent row, impregnating the Wrapping of the several conductors and the insulating strips With a phenolic condensation product, subjecting the body thus formed to the simultaneous action of heat and pressure, wrapping the body thus treated With further insulating material, including an outer layer of paper, impregnating this material with a phenolic condensation product and subjecting the body thus formed to the simultaneous action of heat and pressure to intimately unite all of its component parts.

In testimony whereof, I have hereunto subscribed my name this 23rd day of August, 1917.

JESSE E. MATEER. 

